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To stretch a certain spring by \(2.5 \mathrm{~cm}\) from its equilibrium position requires \(8.0 \mathrm{~J}\) of work. (a) What is the force constant of this spring? (b) What was the maximum force required to stretch it by that distance?

Short Answer

Expert verified
The spring constant is 25600 N/m, and the maximum force required is 640 N.

Step by step solution

01

Understanding Hooke's Law

Hooke's Law describes the force needed to stretch or compress a spring. The force exerted by the spring is given by \( F = kx \), where \( F \) is the force, \( k \) is the spring constant, and \( x \) is the displacement from the equilibrium position.
02

Work-Energy Principle for Springs

The work done on a spring when it is stretched or compressed is given by \( W = \frac{1}{2} k x^2 \). Here, \( W = 8.0 \) J and \( x = 2.5 \) cm, which needs to be converted to meters: \( x = 0.025 \) m.
03

Solving for Spring Constant

Using the work-energy principle: \( W = \frac{1}{2} k x^2 \), substitute the given values:\[ 8.0 = \frac{1}{2} k (0.025)^2 \]Solving for \( k \), we get:\[ k = \frac{2 imes 8.0}{(0.025)^2} \]\[ k = \frac{16}{0.000625} \]\[ k = 25600 \, \mathrm{N/m} \].
04

Calculating Maximum Force

Once we have the spring constant, the maximum force can be found using Hooke's Law: \( F = kx \). Substituting the known values:\[ F = 25600 \times 0.025 \]\[ F = 640 \, \mathrm{N} \].

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Spring Constant
The spring constant, also known as the stiffness or force constant, is a measure of a spring's resistance to being compressed or stretched. In the context of Hooke's Law, it's symbolized by the letter "\( k \)". Simply put, it tells us how tight or loose a spring is. A higher spring constant means the spring is stiffer. It's harder to stretch or compress it.

In the exercise, we found the spring constant by using the work-energy principle. The relation given by the formula \( W = \frac{1}{2} k x^2 \) helped us in this process, where \( W \) is the work done to stretch or compress the spring, \( k \) is the spring constant, and \( x \) is the displacement from the equilibrium position. By plugging in the values for the work done and displacement, we calculated \( k \) to be 25600 \( \mathrm{N/m} \).

Understanding the spring constant is crucial because it helps you determine how a spring will behave under different forces and scenarios. Whether designing a suspension system or a simple mechanical toy, knowing how to determine the spring constant is fundamental.
Work-Energy Principle
The work-energy principle is a vital concept in physics. It states that work done on an object results in a change in its kinetic energy. For springs, this principle is captured in the formula \( W = \frac{1}{2} k x^2 \). This equation relates the work done on the spring to the spring constant and the displacement.

In our problem, 8.0 j of work was used to stretch the spring by 2.5 cm. Converting the displacement to meters to fit the scientific standard resulted in \( x = 0.025 \) m. We used the work-energy relationship to find the spring constant by rearranging the formula:
  • Step 1: \( W = \frac{1}{2} k x^2 \)
  • Step 2: Substitute the known values to solve for \( k \).
  • Step 3: Rearrange and solve, getting \( k = 25600 \mathrm{\ N/m} \).
This principle is key because it helps connect the energy needed to change the spring's shape to the force it exerts. Understanding this can also help in understanding energy transfer scenarios in engineering and everyday physics problems.
Maximum Force
The maximum force is the greatest force applied to stretch or compress a spring during the interaction. In our case, this was calculated once we knew the spring constant. We applied Hooke's Law, which states \( F = kx \). This formula guides us in finding out the force exerted by or onto a spring based on the spring constant and displacement.

For our exercise, with a spring constant of 25600 \( \mathrm{N/m} \) and displacement of 0.025 m, the maximum force was determined as follows:
  • Substitute \( k = 25600 \) and \( x = 0.025 \) into Hooke's Law.
  • Calculate \( F = 25600 \times 0.025 = 640 \mathrm{\ N} \).
This calculation shows that the maximum force required to stretch the spring in the exercise was 640 N. Understanding maximum force in spring mechanics helps in designing systems where controlling or measuring force is essential.
Displacement
Displacement refers to how much the spring has been stretched or compressed from its natural (or equilibrium) position. It is typically measured in meters in physics problems to align with the Units of the International System (SI units).

In our exercise, the displacement was given as 2.5 cm, which needed to be converted to meters (0.025 m) for further calculations. This conversion is crucial for maintaining consistency in units when using formulas like Hooke's Law and the work-energy principle.

Displacement plays a significant role in determining the force and energy in spring systems. It directly affects the force exerted by the spring through the relation \( F = kx \) and influences the work done through \( W = \frac{1}{2} k x^2 \).
  • Always convert displacement to meters when working with physics equations.
  • Understand that greater displacement generally requires more energy, following the work-energy principle.
Grasping this concept helps ensure accurate calculations and a deeper understanding of how forces interact with materials like springs.

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Most popular questions from this chapter

A tow truck pulls a car \(5.00 \mathrm{~km}\) along a horizontal roadway using a cable having a tension of \(850 \mathrm{~N}\). (a) How much work does the cable do on the car if it pulls horizontally? If it pulls at \(35.0^{\circ}\) above the horizontal? (b) How much work does the cable do on the tow truck in both cases of part (a)? (c) How much work does gravity do on the car in part (a)?

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